Gait analysis of adult paraplegic rats after spinal cord repair.

This study presents a novel detailed method of analysis of rat gait and uses this method to demonstrate recovery of forward locomotion patterns in adult rats made paraplegic by surgical spinal cord transection and subjected to a novel strategy for spinal cord repair. Six normal rats were compared to five animals in which the cord was transected at T8-T9, and a 5-mm segment of the spinal cord removed, and to seven animals in which, following spinal cord transection and removal of a spinal cord segment, multiple intercostal peripheral nerve bridges were implanted, rerouting pathways from white to gray matter in both directions. The implanted area was filled with fibrin glue containing acidic fibroblast growth factor. Details of the repair strategy have been published (H. Cheng, Y. Cao, and L. Olson, 1996, Science 273: 510-513). Gait analysis was carried out 3 and 4 months after surgery and once in the normal animals. Animals were allowed to walk across a runway with a transparent floor. Each test consisted of five trials, and each trial was videorecorded from underneath. Using frame-by-frame playback, individual footprints were then recorded regarding location and order of limb use, as well as step quality (degree of weight bearing, etc.). These data allowed measuring runway transit time, five different measures of step numbers, all possible temporal patterns of limb use, stride length, and base of support. Transected controls remained paralyzed in the hindlimbs with only occasional reflex hindlimb movements without weight bearing. Animals subjected to the full repair procedure were significantly faster than the controls, used their hindlimbs for 25-30% of the movements, and regained several of the specific limb recruitment patterns used by normal rats. Taken together, the gait analysis data demonstrate remarkable recovery of coordinated gait in the repaired animals, which was significantly better than controls for all relevant parameters, while at the same time clearly inferior to normal rats for most of the examined parameters. We conclude that normal rats use a multitude of interchangeable step sequence patterns, and that our spinal cord repair strategy leads to recovery of some of these patterns following complete spinal cord transection. These data suggest functionally relevant neuronal communication across the lesion.